نتایج جستجو برای: volcanic

تعداد نتایج: 14735  

Journal: :journal of mining and environment 0
a. entezari harsini department of geology, ferdowsi university of mashhad, mashhad, iran s. a. mazaheri department of geology, ferdowsi university of mashhad, mashhad, iran s. saadat department of geology, mashhad branch, islamic azad university, mashhad, iran j. f. santos department of geosciences, geobiotec research unit, university of aveiro, aveiro, portugal

this paper presents the new geochemical isotopes sr and nd, and the mineralization data for the south neyshabour volcanic rocks located in ne iran. based on the chemical classifications, the studied rocks are basaltic trachy andesite, trachy andesite, trachyte, and trachy dacite in composition. all the analyzed volcanic rocks display enrichment in light rare earth elements (lree) relative to th...

2009
Marı́a Charco Antonio G. Camacho Kristy F. Tiampo José Fernández

[1] Mass redistribution and deformation cause spatiotemporal gravity changes in active volcano areas. The ability of the gravity measurements to detect subsurface magma movement as a precursor to volcanic eruptions is greatly enhanced if gravity changes are analyzed and modeled jointly with ground deformation data. One effective tool for this analysis is provided by the gravity and elevation ch...

2015
Timothy J. Halliday John Lynham

We thank Jill Miyamura of Hawai‘i Health Information Corporation for the data. Chaning Jang and Jonathan Sweeney provided expert research assistance. We also thank participants at the University of Hawai Applied Micro Group for useful comments. Finally, de Paula gratefully acknowledges financial support from the European Research Council through Starting Grant 338187 and the Economic and Social...

2014
A. R. Stine P. Huybers

Annual growth ring variations in Arctic trees are often used to reconstruct surface temperature. In general, however, the growth of Arctic vegetation is limited both by temperature and light availability, suggesting that variations in atmospheric transmissivity may also influence tree-ring characteristics. Here we show that Arctic tree-ring density is sensitive to changes in light availability ...

Journal: :Science 2006
V Ramaswamy M D Schwarzkopf W J Randel B D Santer B J Soden G L Stenchikov

Observations reveal that the substantial cooling of the global lower stratosphere over 1979-2003 occurred in two pronounced steplike transitions. These arose in the aftermath of two major volcanic eruptions, with each cooling transition being followed by a period of relatively steady temperatures. Climate model simulations indicate that the space-time structure of the observed cooling is largel...

The northeast region of Birjand is located in Lut structural and geological province. In this area we can distinguish two separate volcanic rock groups: intermediate to acidic volcanic rocks, including dacite, andesite, rhyolite and trachyandesite; and basic rocks, including basaltic andesite, mugearite and basalt. In this region, intermediate to acidic rocks, which belong to the Eocene-Miocene...

تقی‌پور, نادر, حاجی بهرامی, مریم, قربانی, قاسم,

Hamyerd iron deposit is located about 74 km north east of Semnan, in the Jam area. This area is situated in the northern part of Central Iran structural zone. The outcrops are Middle-Eocene volcanic and pyroclastic rocks with andesite to andesite-basalt and tuff composition, which are intruded by some intrusive bodies of monzonite to monzodiorite composition in this area. Iron mineralization is...

2016
Jonathan M. Castro Benoit Cordonnier C. Ian Schipper Hugh Tuffen Tobias S. Baumann Yves Feisel

Magmatic intrusions and volcanic eruptions are intimately related phenomena. Shallow magma intrusion builds subsurface reservoirs that are drained by volcanic eruptions. Thus, the long-held view is that intrusions must precede and feed eruptions. Here we show that explosive eruptions can also cause magma intrusion. We provide an account of a rapidly emplaced laccolith during the 2011 rhyolite e...

2014
JAMES W. HEAD DAVID R. MARCHANT

The early climate of Mars (Noachian Period, the first ~20% of its history) is thought to differ significantly from that of its more recent history (Amazonian Period, the last ~66%) which is characterized by hyperarid, hypothermal conditions that result in mean annual air temperatures (MAAT) well below 0°C, a global cryosphere, minimal melting on the ground surface, and a horizontally stratified...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2016
Hugo Delile Duncan Keenan-Jones Janne Blichert-Toft Jean-Philippe Goiran Florent Arnaud-Godet Paola Romano Francis Albarède

The influence of a sophisticated water distribution system on urban development in Roman times is tested against the impact of Vesuvius volcanic activity, in particular the great eruption of AD 79, on all of the ancient cities of the Bay of Naples (Neapolis). Written accounts on urbanization outside of Rome are scarce and the archaeological record sketchy, especially during the tumultuous fifth...

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